Heat recuperating wall structure for furnaces



Mar ch 21, 1939. v R ms 2,151,358 I HEAT RECUPERATING WALL STRUCTURE FOR FURNACES Filed July 11, 1936 3 Sheets-Sheet 1 INVENTOR LAWRENCE Rfflcmms cm.

'QATTORNEY.

March 21, 1939. 1.. R. ROBINSON HEAT RECUPERATING WALL STRUCTURE FOR FURNACES Filed July 11, 1936 3 Sheets-Sheet 2 INVENTOR. LAWRENCE RRnnmsun.

QATTORNEY.

March 21, 1939. L. R. ROBINSON 2,151,353

4 HEAT RECUPERATING WALL STRUCTURE FOR FURNACES Filed July 11, 1936 3 Sheets-Sheet 3 INVENTOR. LAWRENCE Rlnamsnu.

'ATFORNEY.

Patented Mar. 21, 1939 PATENT OFFICE 1 Claim. (01. 263-15) This invention relates to furnaces and more particularly to industrial furnaces wherein air is drawn or passed over the outside of the furnace for the purposes of recuperating part of the heat losses or of preventing heating of the work shop, the air, inturn, being usedas preheated air for purposesof combustion, for drying kilns, or for mixture with'the products from the furnace for drying and heating operations.

in V For purposes of illustration the invention is illustrated in connection with a grateless gravity feed furnace utilized for producing heat for drying kilns and the like, the use of the invention in connection with firing kilns, heat treating furnaces, and other furnace structures being readily apparent therefrom.

One of the principal objects of the present invention is to provide for a more efficient flow of the air passing over the exterior of the furnace. 20 A correlative object is to provide for a continuous expansion-of the air in the direction of travel along the exterior of the furnace so as to compensate for the increase in the volume thereof due to heating.

5 Another object is to reduce the power or draught required for maintaining the desired volume of flow of the air.

Other objects and advantages will become apparent from the following specification wherein 30 reference is made to the drawings in which Fig. 1 is a vertical sectional view through a furnace structure embodying the principles of the present invention; and is taken on a plane indicated by the line 1-4 in Fig. 3;

35 Fig. 2 is a front end elevation of the structure illustrated in Fig. 1, viewed from the line 2-2 thereof, and is partly in section for clearness in illustration Fig. 3 is a horizontal sectional view taken on 40 the line 3-3 of Fig. 2.

Referring to the drawings, the furnace comprises generally an arched top wall I which is preferably covered with a sand or other refractory pack 2 in the customary manner, the top 45 wall merging with side walls 3 and a rear wall 4.- At the front of the enclosure thus provided is a front wall 5 having a firing passage 50. and

, an ash removal passage 5b. Within the furnace is a main transverse partition wall 1 having 50 a plurality of passages 8 permitting passage of the products of combustion therethrough.

Forwardly from the wall I is an upright baffie wall 9 the wall being in spaced relation to the front wall 5 and the partition wall 1 of the fur- 55 nace so that gases from the fuel bed, which is charge compartment ill from which the heated products discharge through a passage II at the lower portion of the compartment Ill. The gases from the passage l I then flow outwardly through a tunnel l2, as indicated by the arrows I3, the 10 tunnel leading to the drying kiln or other structure in which the resultant heating media are to be supplied for use. Also leading from the compartment I0 is a suitable stack I4.

In order to recuperate the heat from the furl6 nace, or to prevent its escape into the work shop, as the case may be, the furnace is enclosed at all except the front wall with a recuperating wall, designated generally as 26, which comprises a top wall portion 28a, side wall portions 20b and a rear wall portion 200. The wall portions 20a, 20b and 200 are arranged in spaced relation to the corresponding walls of the furnace structure and define therewith continuous air passages 2| a, Zlb and, 2lc, respectively, these passages being intercommunicating. The recuperating wall structure 20 is so arranged with respect to the furnace that each of the passages Zla, 2lb and Me is gradually expanding in the direction of flow of air therethrough so that, as the air is drawn therethrough and heated by contact with the furnace, it may expand freely. Thus back pressures are eliminated and a larger flow of air may be obtained for a given amount of power or draught.

In the form illustrated, air is admitted into the space 2la through suitable ports 22 near the front of the furnace and flows, as indicated by the arrows 23, rearwardly of the furnace. Correspondingly ports 24 are provided at the front of the furnace for admitting air into the spaces Zlb through which it flows, as indicated by the arrows 25, toward the rear of the furnace. The air from both of the spaces 2Ia and 2 lb, in turn, enters the passage Zlc which is likewise expanded in the direction of flow of the air, as described. To cause the flow of air through the passages, suitable pressure means may be provided at the inlets 22 and 24, but in the form illustrated, the flow is created by suction at the discharge end of the passage 2lc. Since in the particular installation shown for illustration, the air is drawn from the tunnel l2 to drying kilns and the like, this negative pressure is utilized for creating the flow through the passages around the furnace.

For this purpose, the lower end of the passage Zlc has a series of ports 21 opening into the tunnel 12 with the result that the heated products from the furnace are mixed with preheated air which is drawn efliciently from around the outside of the furnace, thus augmenting the volume of heated gases delivered to the drying kilns and the like.

In those instances wherein the preheated air is to be used for sustaining primary combustion in the furnace, obviously the lower end of the passage He may be uncomrnunicated from the tunnel I2 and suitable air ducts connected there to and leading to the firebox of the furnace or to such places as desired for use, a blower or suction fan being provided in the line, if desired.

Secondary combustion may also take place within the tunnel I2 so as to eliminate the possible loss of unconsumed combustible matter in the gases passing through the furnace into the tunnel because of the additional preheated air supplied through the ports 21. As a result of providing in combination with the furnace in which heat is to be recuperated from the exterior of the furnace structure, a recuperating wall which defines with the furnace structure a gradually expanding passage in the direction of flow,

the flow of air is greatly augmented, less power is required for a given volume of air and the air is more uniformly heated. Again, since expansion is permitted freely, a greater quantity of heat is absorbed with a consequent decrease in the radiation losses from the furnace.

Having thus described my invention,

I claim:

A furnace structure comprising a combustion chamber having heat insulating side, top and rear walls, an enclosing boxlike recuperating wall structure enclosing said combustion chamber and having side, top and rear walls spaced from the side, top and rear walls respectively of the combustion chamber and defining with the respective walls of. the combustion chamber intercommunicating passages means for withdrawing air from the space between the combustion chamber and the recuperating wall structure near the bottom of the rear wall of the combustion chamber, the space between each wall of the chamber and its associated recuperating wall being gradually expanded. in the direction of flow of air therethrough, and means for admitting air between the side and top walls of the combustion chamber and the associated recuperating walls adjacent the front of the combustion chamber.

LAWRENCE R. ROBINSON. 

